1. Field of the Invention
The present invention relates to a tri-gated molecular field effect transistor (FET) and a method of fabricating the same and, more particularly, to a tri-gated molecular FET and a method of fabricating the same which can maximize a gate effect on a channel region having a length of several nm or less.
2. Discussion of Related Art
In recent years, the amount of information has increased exponentially as information and communication technologies have developed. In order to process the information, the integration density of silicon-based semiconductor devices also has been on the increase owing to the advancement of semiconductor technologies.
However, in the case of a top-down technique that scales down the size and linewidth of devices by improving the resolution of a photolithography process, as the channel length is reaching the level of several nm, the integration and performance of devices are limitedly improved while the cost of investment in equipment is rapidly augmented.
To overcome the drawback and produce economical nanoscale electronic devices, a bottom-up technique of fabricating molecular devices using molecular intrinsic properties, such as self-assembly and self-replication, has been proposed as an alternative option.
In a conventional molecular field effect transistor (FET), a channel having a length of several nm or less is formed between a source electrode and a drain electrode using organic molecules or nanoparticles having semiconductivity. This molecular FET is a three-terminal molecular device that controls the flow of electrons in the channel by use of a gate electrode, and an indispensable element for moleculescale fabrication of switching circuits, logic circuits, and ring oscillators.
In this conventional molecular FET, monomolecules or nanoparticles are inserted between the source and drain electrodes, thereby forming the channel through which electrons are transported. In this case, a gap in which the monomolecules or nanoparticles are inserted needs to be formed between the source and drain electrodes beforehand. To form the gap, an electrode line having a width of several nm may be formed and cut using electromigration. Alternatively, a gap having a greater width may be formed using electron-beam (e-beam) lithography, and then an electrode material may be additionally coated therein using electrochemical deposition such that the gap has a desired width.
In other words, a gate insulating layer formed of oxide and the gate electrode formed of silicon or a metal are sequentially formed on one lateral surface of the channel. Thus, the conventional molecular FET is structured such that current supplied between the source and drain electrodes can be controlled by varying the voltage applied to the gate electrode.
As described above, the conventional molecular FET includes the gate electrode that is contacted with only on one lateral surface of the channel that connects the source and drain electrodes. For this reason, when the gate voltage is changed, there may be no significant difference in the current flowing between the source and drain electrodes.